GEOLOGY OF CENTRAL MINAS GERAES, BRAZIL 353 



belt, especially in the northern part, it is the only one of the Algon- 

 kian formations present, being bounded on both the east and the 

 west by rocks of the basement complex. In detail the distribution 

 of the Caraga quartzite is as follows: Beginning at the southwest, 

 a belt of quartzite dipping to the southeast runs northeastward to 

 a point about northwest of Congonhas do Campo where it turns 

 northward and continues with great uniformity to about the lati- 

 tude of Bello Horizonte where it is cut off sharply by a northeast- 

 southwest belt of sediments. To the east of it, and approximately 

 parallel with it, is a shorter quartzite belt also dipping to the east. 

 Between the two belts are areas of iron formation and Piracicaba 

 schist, while to the east and west of them are granite, gneiss, and 

 schist of the basement complex. From the structure it is presumed 

 that these two north- and south-striking quartzite belts are on 

 opposite limbs of an overturned syncline dipping to the east. 

 Both belts are well shown in the topography, the western one 

 appearing as the Serra da Boa Morte and the eastern one forming 

 the high hills west of Itabira do Campo. 



Beginning with Serra do Ouro Branco near Miguel Burnier is an 

 east-west belt of quartzite somewhat more irregular than are the 

 north-south belts, being broken at several places, and varying in 

 strike in different parts, from northwest-southeast to northeast- 

 southwest. It continues eastward to a point southeast of Ouro 

 Preto where it is cut off by rocks of the basement complex. South 

 of it, unconformably underlying it, are schist, gneiss, and granite 

 of the basement complex. Some distance to the north of it and 

 parallel to it is another quartzite belt dipping southward, being 

 underlain and bounded on the north by granite, gneiss, and schist. 

 Between these two quartzite bands are areas of iron formation and 

 Piracicaba schist, so that here occurs an east-west syncline differ- 

 ing from the north-south syncline before mentioned in being broad 

 and open. The southern limb forms the prominent Serra do Ouro 

 Branco while the northern limb is not very marked topographically, 

 being mainly composed of quartzite schist not very resistant to 

 erosion. 



The northern of these quartzite belts continues westward 

 beyond Miguel Burnier and eastward to Ouro Preto where it 



